We plan on continuing our analysis of the mechanism by which the segmentation gene fushi tarazu (ftz) is temporally and spatially regulated at the level of transcription. Our past work has focused on the cis acting control elements present in the zebra promoter element. We found that two regulatory sites when present as an array of individual oligonucleotide binding sites were capable of reconstructing the striped pattern of ftz transcription in the embryo. These two regulatory elements have thus become the focus of our current work and this continuation proposal. One of these two sites is termed the dual element (DE) because it provides both an activation function as well as a repressor function. The other site is termed repressor element-1 (RE-1) because it seems to provide only a repressor function. We have cloned and partially characterized two genes whose products bind to the DE. They are both novel members of the steroid receptor super- family, and possess a unique amino acid sequence in their DNA binding domain. The proteins that we have identified which bind to the RE-1 include the giant protein and a novel gene product which contains a basic region than is only now being characterized. In the future we plan to carry out a detailed analysis of these and other potential regulators of ftz transcription to understand the mechanism by which they function to control transcription.